objspace_dump.c: include object's gc flags in dump

* ext/objspace/objspace_dump.c (dump_object): include fstring flag on
  strings. include gc flags (old, remembered, wb_protected) on all objects.
* ext/objspace/objspace_dump.c (Init_objspace_dump): initialize lazy
  IDs before first use.
* gc.c (rb_obj_gc_flags): new function to retrieve object flags
* internal.h (RB_OBJ_GC_FLAGS_MAX): maximum flags allowed for one obj
* test/objspace/test_objspace.rb (test_dump_flags): test for above
* test/objspace/test_objspace.rb (test_trace_object_allocations):
  resolve name before dump (for rb_class_path_cached)

git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/trunk@44105 b2dd03c8-39d4-4d8f-98ff-823fe69b080e